Fall protection systems, or fall arrest systems, are commonly used to prevent accidents involving falls from elevated work environments, e.g., the tops of railroad cars, tanker trucks, etc., or from stationary structures, such as rooftops of buildings, silos and other structures that, while being traversed, provide fall hazards. To that end, it is a common practice for workers to wear a harness that is attached to a support assembly by means of a cable known as a lanyard or “lifeline.” The safety harness is normally manufactured of nylon webbing material and is designed to distribute the loading stresses of a fall to prevent serious injury to the worker.
In order to enable the worker to move readily about the vehicle or structure being traversed many fall protection systems include a rolling trolley to which the worker is tethered by a retractable lanyard and associated safety harness. In some systems the trolley is mounted to roll along an elevated cable (steel or synthetic material) that is strung between two or more anchor points. Other systems make use of an elevated track, e.g., I-beam, on which the trolley is mounted. The trolley in the I-beam system is typically a four-wheeled device that is designed to ride on the lower leg or flange of the I-beam, and includes an attachment point to secure the lifeline to the trolley.
Examples of prior art fall protection systems are shown and described in the following U.S. patents.
U.S. Pat. No. 6,269,904 (Morhaus) discloses a rail assembly having an I-beam supported on the bottom of a truss member which is mounted between support members over the elevated surface being worked on. A trolley is provided with wheels arranged to engage an upper side of the bottom flange of the I-beam such that the trolley can move along the I-beam in response to movement of the attached worker.
U.S. Pat. No. 6,334,507 (Westerweel) discloses a cable assembly having parallel and generally horizontal anchoring lines spaced apart above the elevated surface. A trolley is provided with rollers arranged to allow movement along the longitudinal anchoring lines.
U.S. Pat. No. 6,467,574 (Lara) discloses a sliding member for use with a horizontal life-line including a cable extending along a wall and connected thereto by supports. The sliding member includes a body having a channel in which the cable slides and a handle adapted to receive one end of a lanyard whose other end is connected to a safety harness. A movable jaw is provided as part of the sliding member and is adapted to form a slot in the channel to enable the sliding member to be mounted on the cable. The sliding member also includes a mechanism for holding the movable jaw slightly open in an intermediate first configuration to form a slot having a thickness greater than the thickness of supports for the cable and a device for opening the movable jaw to increase the size of the slot in an open second configuration. When the sliding member is In the open second configuration it is adapted to be mounted on the cable. An element for automatically placing the sliding member in a safety configuration if traction is applied to the handle is also included. That element enables the movable jaw to pivot so that the slot is completely blocked.
U.S. Pat. No. 7,347,300 (Renton) discloses a traveler for a fall arrest system including a body having a bore and a slot narrower than the bore linking the bore to the exterior of the body. A load member is connected to the body for pivotal movement relative to the body and suitable for attachment to fall safety equipment.
U.S. Published Application No. 2006/0156944 discloses a rail and trolley apparatus having a trolley movable along a horizontally supported rail assembly for use as a fall protection system. The trolley includes a pair of wheels arranged to engage opposing bearing surfaces in each of two channels provided in the rail assembly. Each bearing surface has a central portion and two side portions shaped to fit flush against a curved edge surface of each wheel. This allows the wheels to bear against the surfaces in multiple directions, thereby allowing rolling motion of the trolley along the rail assembly as well as loading of the trolley in any direction not parallel to that motion to enable the apparatus to be oriented at any angle about a longitudinal axis thereof during installation.
Other U.S. patents disclosing fall arrest systems are U.S. Pat. No. 6,378,651 (Ecker et al.); U.S. Pat. No. 6,488,118 (Corriveau); U.S. Pat. No. 6,547,033 (Cheval); U.S. Pat. No. 6,837,337 (Thomas et al.); U.S. Pat. No. 7,111,707 (Reeves); and U.S. Pat. No. 7,341,159 (Nelson).
While the aforementioned prior art systems employing a movable trolley may be generally suitable for their intended purpose of preventing a falling worker from being injured, such systems merely address the issue of preventing the worker from falling to the ground, i.e., they suspend the worker from the elevated track or cable until help arrives. These prior art systems do not enable the worker to move himself/herself along the elevated track to some safe position from which the worker can dismount after their fall has been arrested. In particular, even though the prior art trolleys are arranged to readily roll along the track, the person suspended from such a trolley cannot move it along the track or cable unless there is some stationary structure located within reach of the worker to which he/she may grasp to pull or push against. Merely swinging one's body when suspended from a movable trolley will not effect the movement of the trolley along the track.
Thus, a need presently exists for a fall arresting system trolley which enables a person suspended from the trolley to move it along the track to a position of safety. The subject invention addresses that need.
All references cited herein are incorporated herein by reference in their entireties.